TimC is very right...check the U-shape elevator brace....Mine was slightly bent and since the Twist was my 1st ARF, an "experienced" builder demonstrated me how to build an ARF. He forgot to check this elevator brace and now my elevator is slightly bent. It is minor, and obviously does not effect my baby's flight performance, but of course you always try to build the plane PERFECT!!
So follow Tim's advice...CHECK the brace before you mount it
Also, when placing the tank in the fuselage....do not wrap it too tight in foam when installing the tank!!!! I had air bubbles in the fuel line when running 2 different engines, and it took us few weeks to find out the problem!!!
Just snug...that's all!! and then secure the back with a popsickle stick or so
The engine caused ever so slight vibration enough to cause the fuel to foam!!
...just my .02